Need help with your rail lingo? Here are some terms and definitions commonly used in the rail world.
A frame: Type of flat car designed with bulkheads on each end and a center beam structure connected to each bulkhead to support the load so that it does not shift during movement.
Angle cock: Appliance used for the purpose of opening or closing brake pipe on ends of cars, rear ends of tenders and front ends of switch engines so equipped. Provision is made for supporting hose at the proper angle.
Auto rack: Rail car designed to transport automobiles (also called Rack, Tri, Bi)
Balloon track: Railroad track in the shape of a teardrop used to reverse the direction of a train.
Bullfrog or Bullfrog junction: Switch junction that connects the Tacoma Rail, Union Pacific and BNSF Railway tracks.
Controlled track: Track upon which the railroad's operating rules require that all movements of trains must be authorized by a train dispatcher or a control operator.
Dark territory: Series of rail miles ungoverned by signals and unable to transmit or receive radio or cellular phone signals.
Dump the air: Signal to apply the emergency air brake/brakes to a car/cars or locomotive or both.
Fouling a track (OTS): Placement of an individual or item in such proximity to a track that it could be struck by a moving train or on-track equipment or is within four feet of the field side of the near running rail. It could be farther than four feet from the rail and still be fouling the track if its position or actions could cause movement into the four-foot zone, or if there were any possibility of the individual being struck by a part of a moving train or on track machine that might extend more than four feet outside the rail. An example would be an individual working on the slope of a cut above the track, where a slip could cause movement into the track area.
F.R.E.D.: Flashing Rear End Device; used on mainline trains, end of train telemetry device (also called EOT or End of Train device).
Frog: Center fixed cross of a switch that allows connecting rails to intersect and cross.
Fusee: Combustible torches which burn (red, yellow or green) for 10 to 15 minutes as warning signals to other trains when touched off and placed or thrown on the ground by train service employees.
Glad hand: Metal attachments to which train line air hoses connect.
Hopper: Steel-sided car with a bottom that opens to allow unloading of coal, gravel, etc.
Hy-rail vehicle: Specially designed maintenance and inspection vehicles that can operate on the highway and the rails.
Interchange point: The point at which two or more railroads join. Traffic is passed from one road to another at interchange points.
Main line: The part of a railroad exclusive of switch tracks, branches, yards and terminals.
Rip track: Track designated for rail car repair.
Rolling resistance: Resistance that is made up of wheel friction, journal friction and wind resistance. It is non-recoverable.
Spot: Exact location for a car to be loaded or unloaded.
Switch: Mechanical device used to move switch rail in a turnout; also, the act of rearranging car order or spotting cars.
Target: A visible plate on a switch stand that indicates position of the switch points.
Wye: Track configuration used in lieu of a turntable for turning engines, cars and trains around or reversing locomotive/train direction
Yard: System of tracks, other than main tracks and sidings, within defined limits; used for making up trains, storing cars and other purposes.
Yard limits (YL): Portion of main track designated by yard limit signs and timetable special instructions or a track bulletin.
More definitions can be found here.